The Mercedes driver now has a 28-point cushion over the German with six of the 20 races remaining.
Red Bull’s Daniel Ricciardo, who also emerged from the opening lap carnage unscathed, was second for the third year in a row with Finland’s Valtteri Bottas completing the podium for Mercedes.
“I came here today really thinking it was about damage limitation, and we’ve come out ahead. So I’m very grateful,” he said later.
The Briton cashed in after Vettel, Ferrari team mate Kimi Raikkonen and Red Bull’s front row contender Max Verstappen smashed into each other as they raced off the wet starting grid and into the first corner.
Raikkonen had made a storming start from fourth, Vettel a less impressive one from pole position while Verstappen went for the middle ground and was caught in a Ferrari sandwich as they converged.